<!DOCTYPE html>
<html lang="zh-cmn-Hans">

<head>
    <!-- Required meta tags -->
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width,initial-scale=1,shrink-to-fit=no" />
    <!-- Bootstrap CSS -->
    <link rel="stylesheet" href="../bootstrap-4.5.0-dist/css/bootstrap.min.css">
    <title>元素size变更</title>
    <style>
        .my-container {
            width: 200px;
            height: 200px;
            background: #ddd;
            margin-bottom: 5px;
        }
    </style>
</head>

<body>

    <div class="my-container">
        <div class="bg-primary w-25 h-50">w-25:设置宽25% h-50:设置高50%</div>
    </div>
    <div class="my-container">
        <div class="bg-success w-75 h-100">w-75:设置宽75% h-100:设置高100%</div>
    </div>

    <!-- Optional JavaScript -->
    <!-- jQuery first, then Popper.js, then Bootstrap JS -->
    <script src="../bootstrap-4.5.0-dist/others/jquery-3.5.1.min.js"></script>
    <script src="../bootstrap-4.5.0-dist/others/popper.min.js"></script>
    <script src="../bootstrap-4.5.0-dist/js/bootstrap.min.js"></script>
</body>

</html>